The existing safety design for a winch mainly uses overload detection. For example, safety is achieved through overload alarms. Even though the safety of using the winch is improved to a certain extent, the alarm prompt is given only when an overload happens. The problems of the existing alarm device are provided as below. On the one hand, the alarm occurs suddenly, and a user is not psychologically prepared, and therefore a sudden alarm can easily cause a certain impact to the psychology of the user, so that the alarm causes a certain discomfort by startling the user. Especially for a novice, the alarm and accompanying fright and shock can even cause the user to feel disoriented after the alarm is received, so that the user may cause a safety accident due to disorientation. On the other hand, the change in load during operation is not readily apparent to the user, and therefore, the user has no way to proactively control the winch. Lack of proactive initiative results in a decreased safety in operation of the winch.